**4. Conclusions**

In this paper, the effect of second velocity slip on the MHD flow of nanofluid in a porous medium with homogeneous-heterogeneous reactions has been analyzed. In the absence of the second slip, remarkable differences have been detected between the current exact results and those in the literature for the skin friction coefficient. For velocity, it has been found that the Ag-water nanofluid is lower than the other four kinds of nanofluids. For concentration, the exact solution has been given when only the heterogeneous reaction occurs. When both of the homogenous and heterogenous reactions take place, the concentration equation has been numerically solved. The concentration reduces with the strengthening of the heterogenous reaction and also with the increase in the Schmidt parameter, where the Ag-water nanofluid is of lower concentration than the Cu-water nanofluid.

**Author Contributions:** Conceptualization, F.A. and S.M.K.; methodology, F.A.; software, A.E.; validation, A.E.; project administration, F.A.; funding acquisition, F.A.

**Funding:** This research was funded by the Deanship of Scientific Research (DSR), University of Tabuk, Tabuk, Saudi Arabia, gran<sup>t</sup> number 0074-1439-S.

**Conflicts of Interest:** The authors declare no conflict of interest.
